Lesions to the inferior parietal lobule (IPL) in humans from stroke, cerebral trauma, or tumors, produce deficits in complex cortical functions including spatial perception and visuomotor integration. Similar deficits are found with lesions to IPL (also known as area 7) in monkeys, indicating that monkeys provide an appropriate model for beginning to understand the function of this area in humans. In the experiments in this proposal we will examine the role of IPL in visuomotor and spatial functions by recording from and microstimulating this area in awake, behaving monkeys. These experiments will investigate the role of this area in the processing of spatial information, with special emphasis on its role in coordinate transformations. Previous experiments in this area indicated that eye position and retinal position information converged onto single cells and may produce a representation of visual space in head-centered coordinates. One set of experiments will examine the possibility that activity related to head position is also found for these same cells, and is integrated in a similar way to the eye position signals, consistent with an encoding of locations in body-centered coordinates. We will also examine if the saccade-related activity in the lateral intraparietal area (LIP) is coding gaze shifts, which can include combined eye and head movements, rather than simply eye movements. In a second set of experiments related to coordinate transformations, we will examine if a newly found auditory-related activity in area IPL is coded in head or retinal coordinates, and if this activity is modulated by eye position in a similar way to the modulation for visual signals by eye position. These experiments may find that more than one modality uses the same coordinate transformation machinery in this area and would represent one of the first examples of how modalities are associated in the cortex. In another group of experiments we will examine the functional organization of IPL using cortical microstimulation techniques. These experiments will provide new data on the role of area LIP in eye movement functions. We will also examine the topographic organization of evoked responses in the different cortical areas in IPL to see if they contain orderly retinotopic or spatiotopic representations. In a final group of experiments we will examine the role of IPL in the formation of motor plans. We will be interested in a memory-linked activity that is prevalent in this area, and we will test the hypothesis that this activity is a neural correlate of the intention to make movements. These experiments will help us to understand the fundamental problem of how coordinates are transformed in proceeding from sensory input to motor output. They will also help us to understand how high level cortical functions such as motor plans are processed in this visuomotor pathway.